Mankind takes on godlike powers: to feed billions of people, reshape the landscape, re-engineer the human body. The greatest power of all was unleashed over Hiroshima on August 6, 1945. Since entering the Atomic Age we've been living between eternity and oblivion. But at the same time, we've become more connected as a species. 100,000 years ago there were a few thousand hunter-gatherers on the African savannah. Today there are 7 billion of us in every corner of the globe. It's been an amazing journey.